Department Seminar

In todays world, side-channel attacks have become one of the most
serious threats on standard cryptosystems in practice. Instead of targeting the
mathematical structure that is usually sound and robust, these attacks attempt to gain
information about the secret key from the leakage of the physical implementation of
the algorithm itself. Among these attacks, the power analysis and timing attacks have
received significant attention as they are highly powerful and do not usually require
the knowledge of implementation on the target device on which the attack is
performed.

The talk will first focus on characterization of crypto-primitives called block cipher
S-boxes for power analysis resilience. In this part, the relation between cryptographic
parameters of coordinate functions of S-boxes that define the power-analysis
resilience will be addressed. Based on such properties, a class of S-boxes will be
proposed that have improved power-analysis resilience as compared to standard
S-boxes such as AES Rijndael S-box along with a marginal tradeoff of classical
cryptographic properties.

The next part of the talk will discuss about constructions of rotation symmetric
S-boxes (RSSBs) that have improved power analysis resilience along with good
cryptographic properties like high nonlinearity, small global avalanche characteristics
and high algebraic degree. The evaluation of security metric called success rate of
DPA dversary on the proposed class of RSSBs show that as compared to Rijndael
S-box, a side-channel adversary requires more queries to exploit the information
leakage.